Figure 2
Base calling determined by entropy. A. Probability simplex for a 3-letter alphabet (A = blue, C = red, G = green). Each point in the triangle is a probability triplet (PA, PC, PG) represented by the corresponding color mixture. Blue lines are iso-entropic levels, black lines are the cutoffs between the various IUPAC codes. These correspond to midpoints in the state variable (S = 2h). B. Distribution of entropy per base across 10 tiles on 36 bases. Red lines at the bottom indicate the IUPAC cutoffs. Mass within each segment is indicated in red.